:root {
    --bg: #0b0f17;
    --bg-elevated: #121828;
    --bg-card: #161d2e;
    --border: #253049;
    --text: #e6ebf5;
    --text-muted: #93a0bd;
    --primary: #6366f1;
    --primary-hover: #7c7ff5;
    --success: #22c55e;
    --danger: #ef4444;
    --warning: #f59e0b;
    --radius: 12px;
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-serif: "Fraunces", Georgia, "Times New Roman", serif;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    color: var(--text);
    font-family: var(--font);
    line-height: 1.55;
}

a { color: inherit; text-decoration: none; }

/* ── Top nav ──────────────────────────────────────────────── */
.top-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 12px 24px;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 50;
}
.nav-left, .nav-center, .nav-right { display: flex; align-items: center; gap: 18px; }
.sidebar-toggle {
    background: transparent; border: 1px solid var(--border); color: var(--text-muted);
    border-radius: 8px; width: 32px; height: 32px; cursor: pointer; display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.sidebar-toggle:hover { color: var(--text); border-color: var(--primary); }
.sidebar-toggle.active { color: var(--primary); border-color: var(--primary); }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 18px; color: var(--text); }
.brand i { color: var(--primary); }
.nav-link { color: var(--text-muted); font-size: 14px; display: flex; align-items: center; gap: 6px; padding: 6px 4px; border-bottom: 2px solid transparent; }
.nav-link:hover { color: var(--text); }
.nav-link.active { color: var(--text); border-bottom-color: var(--primary); }
.nav-vscode-badge { color: var(--success); font-size: 12px; margin-left: -2px; }
.nav-progress { display: flex; align-items: center; gap: 6px; font-size: 13px; color: var(--success); font-weight: 600; }
.sound-toggle {
    background: transparent; border: 1px solid var(--border); color: var(--text-muted);
    border-radius: 8px; width: 32px; height: 32px; cursor: pointer; display: flex; align-items: center; justify-content: center;
}
.sound-toggle.muted { color: var(--danger); }
.sound-toggle:hover { color: var(--text); border-color: var(--primary); }

/* ── App shell: sidebar + content ─────────────────────────── */
.app-shell { display: flex; align-items: flex-start; }

.sidebar {
    width: 280px; flex-shrink: 0; border-right: 1px solid var(--border); background: var(--bg-elevated);
    position: sticky; top: 57px; align-self: flex-start; padding: 14px 0;
    transition: width .2s ease, padding .2s ease, opacity .15s ease; box-sizing: border-box;
}
body.sidebar-collapsed .sidebar {
    width: 0; min-width: 0; padding: 0; border-right: none; opacity: 0; overflow: hidden; pointer-events: none;
}
.sidebar-head {
    display: flex; align-items: center; justify-content: space-between; padding: 4px 16px 12px;
    font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: .05em; color: var(--text-muted);
    border-bottom: 1px solid var(--border); margin-bottom: 8px;
}
.sidebar-head-progress { color: var(--success); }
.sidebar-category { margin-bottom: 14px; }
.sidebar-category-head {
    display: flex; align-items: center; gap: 8px; padding: 6px 16px; font-size: 12.5px; font-weight: 700;
    color: var(--text); border-left: 3px solid var(--accent, var(--primary));
}
.sidebar-category-icon { font-size: 14px; }
.sidebar-module { margin: 2px 0 8px; }
.sidebar-module-title {
    display: block; padding: 6px 16px 4px 27px; font-size: 11.5px; font-weight: 700; color: var(--text-muted);
    text-transform: uppercase; letter-spacing: .03em;
}
.sidebar-module-title:hover, .sidebar-module-title.active { color: var(--primary); }
.sidebar-lesson {
    display: flex; align-items: center; gap: 8px; padding: 7px 16px 7px 27px; font-size: 13px; color: var(--text-muted);
    border-left: 2px solid transparent;
}
.sidebar-lesson:hover { color: var(--text); background: rgba(255,255,255,.03); }
.sidebar-lesson.active { color: var(--text); background: rgba(99,102,241,.12); border-left-color: var(--primary); font-weight: 600; }
.sidebar-lesson.done .sidebar-lesson-check { color: var(--success); }
.sidebar-lesson-num {
    width: 16px; height: 16px; border-radius: 50%; border: 1px solid var(--border); font-size: 9px;
    display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.sidebar-lesson-check { font-size: 13px; width: 16px; text-align: center; flex-shrink: 0; }
.sidebar-lesson-title { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.sidebar-category summary { list-style: none; cursor: pointer; }
.sidebar-category summary::-webkit-details-marker { display: none; }
.sidebar-category-head { position: relative; padding-right: 30px; }
.sidebar-category-title { flex: 1; }
.sidebar-category-caret {
    position: absolute; right: 14px; top: 50%; transform: translateY(-50%); font-size: 10px; color: var(--text-muted);
    transition: transform .15s ease;
}
.sidebar-category[open] .sidebar-category-caret { transform: translateY(-50%) rotate(180deg); }

@media (max-width: 900px) {
    .page-body { padding-left: 16px; padding-right: 16px; }
}

.page-body { flex: 1; min-width: 0; padding: 28px 24px 80px; }
.page-body > * { max-width: 1100px; margin-left: auto; margin-right: auto; }


.site-footer {
    text-align: center; color: var(--text-muted); font-size: 12px; padding: 24px; border-top: 1px solid var(--border);
}

/* ── Buttons ──────────────────────────────────────────────── */
.primary-btn, .secondary-btn {
    display: inline-flex; align-items: center; gap: 8px; padding: 10px 18px; border-radius: 10px;
    font-size: 14px; font-weight: 600; cursor: pointer; border: none;
}
.primary-btn { background: var(--primary); color: #fff; }
.primary-btn:hover { background: var(--primary-hover); }
.primary-btn:disabled { opacity: .55; cursor: default; }
.secondary-btn { background: transparent; color: var(--text); border: 1px solid var(--border); }
.secondary-btn:hover { border-color: var(--primary); color: var(--primary); }

.text-link { color: var(--primary); font-weight: 600; font-size: 14px; }
.text-link:hover { text-decoration: underline; }

/* ── Nav user menu ────────────────────────────────────────── */
.nav-user { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text-muted); }
.nav-user-avatar {
    width: 26px; height: 26px; border-radius: 50%; background: var(--primary); color: #fff; font-weight: 700;
    font-size: 12px; display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.nav-user-name { max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-logout-form { display: inline-flex; }
.nav-logout-btn {
    background: transparent; border: 1px solid var(--border); color: var(--text-muted); border-radius: 8px;
    width: 32px; height: 32px; display: flex; align-items: center; justify-content: center; cursor: pointer;
}
.nav-logout-btn:hover { border-color: var(--danger); color: var(--danger); }

/* ── Auth pages (login) ──────────────────────────────────────────── */
.auth-body { margin: 0; background: var(--bg); min-height: 100vh; }
.auth-page { min-height: 100vh; display: flex; align-items: center; justify-content: center; padding: 24px; }
.auth-card {
    width: 100%; max-width: 380px; background: var(--bg-card); border: 1px solid var(--border); border-radius: 16px;
    padding: 32px 30px;
}
.auth-brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--primary); margin-bottom: 18px; }
.auth-card h1 { font-family: var(--font-serif); font-size: 24px; margin: 0 0 6px; }
.auth-subtitle { color: var(--text-muted); font-size: 13px; margin: 0 0 20px; }
.auth-error {
    background: rgba(239,68,68,.12); color: var(--danger); font-size: 13px; padding: 10px 12px; border-radius: 8px;
    margin-bottom: 16px; display: flex; align-items: center; gap: 8px;
}
.auth-form { display: flex; flex-direction: column; gap: 6px; }
.auth-label { font-size: 12px; color: var(--text-muted); margin-top: 8px; }
.auth-input {
    width: 100%; background: var(--bg-elevated); color: var(--text); border: 1px solid var(--border);
    border-radius: 8px; padding: 10px 12px; font-size: 14px; font-family: inherit;
}
.auth-input:focus { outline: none; border-color: var(--primary); }
.auth-submit { width: 100%; justify-content: center; margin-top: 18px; }
.auth-note { font-size: 12px; color: var(--text-muted); margin: 18px 0 0; text-align: center; }
.auth-note code { background: var(--bg-elevated); padding: 1px 6px; border-radius: 5px; }

/* ── Admin: manage users ──────────────────────────────────────────── */
.admin-add-form { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.admin-add-form .auth-input { width: auto; flex: 1; min-width: 160px; }
.admin-role-select { flex: 0 0 110px; }
.admin-user-list { display: flex; flex-direction: column; gap: 8px; }
.admin-user-row {
    display: grid; grid-template-columns: 1.1fr 1.3fr .7fr 1fr 1fr auto auto; gap: 10px; align-items: center;
    background: var(--bg-card); border: 1px solid var(--border); border-radius: 10px; padding: 10px 12px;
}
.admin-user-row-head {
    background: transparent; border: none; padding: 0 12px; font-size: 11px; text-transform: uppercase;
    letter-spacing: .04em; color: var(--text-muted);
}
.admin-edit-form { display: contents; }
.admin-edit-form .auth-input { padding: 8px 10px; font-size: 13px; }
.admin-row-btn { padding: 8px 12px; }
.admin-delete-form { display: flex; }
.admin-delete-btn:hover { border-color: var(--danger); color: var(--danger); }
.admin-progress { display: flex; align-items: center; gap: 10px; }
.admin-progress .progress-bar { flex: 1; }
@media (max-width: 920px) {
    .admin-user-row { grid-template-columns: 1fr; }
    .admin-user-row-head { display: none; }
}

/* ── Progress bars ────────────────────────────────────────── */
.progress-bar { height: 8px; border-radius: 6px; background: var(--border); overflow: hidden; }
.progress-bar.small { height: 5px; margin-top: 8px; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--success)); }

/* ── Hero (home page) ─────────────────────────────────────── */
.hero { display: grid; grid-template-columns: 1.4fr 1fr; gap: 28px; margin-bottom: 36px; align-items: stretch; }
.eyebrow { font-size: 12px; text-transform: uppercase; letter-spacing: .06em; color: var(--primary); font-weight: 700; }
.hero-text h1 { font-size: 34px; margin: 10px 0 14px; line-height: 1.2; }
.hero-text p { color: var(--text-muted); font-size: 15px; max-width: 560px; }
.hero-actions { display: flex; gap: 12px; margin: 18px 0; }
.hero-progress { display: flex; align-items: center; gap: 12px; font-size: 13px; color: var(--text-muted); margin-top: 8px; }
.hero-progress .progress-bar { width: 200px; }
.hero-card {
    background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 22px;
    display: flex; flex-direction: column; gap: 12px;
}
.hero-card h3 { margin: 0; font-size: 16px; display: flex; align-items: center; gap: 8px; }
.hero-card ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; font-size: 14px; color: var(--text); }
.hero-card ul i { color: var(--primary); width: 18px; }
.hero-card-note { font-size: 12px; color: var(--text-muted); margin: 0; }

/* ── Category grid (home) ─────────────────────────────────── */
.category-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin-bottom: 32px; }
.category-card {
    background: var(--bg-card); border: 1px solid var(--border); border-top: 3px solid var(--accent, var(--primary));
    border-radius: var(--radius); padding: 18px;
}
.category-card-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 8px; }
.category-icon { font-size: 22px; }
.badge { font-size: 11px; font-weight: 700; padding: 3px 8px; border-radius: 6px; text-transform: uppercase; letter-spacing: .03em; }
.category-card h3 { margin: 4px 0; font-size: 16px; }
.category-card p { color: var(--text-muted); font-size: 13px; margin: 0 0 12px; }
.category-modules { display: flex; flex-direction: column; gap: 6px; }
.category-modules a { font-size: 13px; color: var(--text); display: flex; justify-content: space-between; padding: 6px 0; border-top: 1px solid var(--border); }
.category-modules a:first-child { border-top: none; }
.category-modules a i { color: var(--text-muted); font-size: 11px; }
.category-modules a:hover { color: var(--primary); }

.insight-callout {
    display: flex; gap: 18px; align-items: flex-start; background: linear-gradient(135deg, #1a1030, #121828);
    border: 1px solid var(--border); border-radius: var(--radius); padding: 22px;
}
.insight-icon { font-size: 26px; color: var(--warning); }
.insight-callout h3 { margin: 0 0 6px; }
.insight-callout p { color: var(--text-muted); font-size: 14px; margin: 0 0 10px; }

/* ── Page header / breadcrumb ─────────────────────────────── */
.page-header { margin-bottom: 24px; }
.page-header h1 { margin: 0 0 6px; font-size: 26px; display: flex; align-items: center; gap: 10px; }
.page-header p { color: var(--text-muted); margin: 0; }
.t-breadcrumb { font-size: 13px; color: var(--text-muted); margin-bottom: 16px; }
.t-breadcrumb a { color: var(--text-muted); }
.t-breadcrumb a:hover { color: var(--primary); }
.t-breadcrumb .sep { margin: 0 6px; }

.empty-state { text-align: center; padding: 60px 20px; color: var(--text-muted); }
.empty-state i { font-size: 34px; color: var(--border); margin-bottom: 12px; }
.empty-state h2 { color: var(--text); margin: 6px 0; }